Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 200237 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 937 PM EST FRI DEC 19 2014 .SYNOPSIS... HIGH PRESSURE CENTERED OVER THE WESTERN GREAT LAKES WILL SLIDE EAST ACROSS PENNSYLVANIA THIS WEEKEND...BRINGING DRY WEATHER WITH LIGHTER WIND. A DEEP UPPER TROUGH AND ASSOCIATED SFC LOW WILL LIFT NORTHEAST THROUGH THE GREAT LAKES DURING THE MIDDLE OF NEXT WEEK LIKELY BRINGING US RAIN AND WIND FOR CHRISTMAS EVE...THEN BLUSTERY AND COLDER CONDITIONS FOR CHRISTMAS DAY WITH SCATTERED SNOW SHOWERS. && .NEAR TERM /UNTIL 8 AM SATURDAY MORNING/... 930 PM UPDATE... CLOUDS AND TEMPS BEHAVING. NO NEED FOR ANYTHING OTHER THAN TINY TWEAKS. 7 PM UPDATE... BIG BREAKS IN CLOUDS LOCALLY. NRLY FLOW IS SHOVING THE CLOUDS DOWN INTO THE POCONOS AND TRYING TO GET THEM INTO LEB/LANC COS. AT THIS POINT...WILL CONTINUE TO COUNT ON THE DOWNSLOPE TO KEEP IT FROM GOING TOTALLY OVC...BUT SOME INCREASE IN CLOUDS OVER THE NEXT FEW HRS IN THE SE IS PROBABLY A GOOD CALL. OTHERWISE...THE SUBSIDENCE IN BETWEEN THE NERN AND SERN PARTS OF THE STATE MAY CONTINUE TO OPEN UP BIGGER BREAKS. WILL HAVE TO TWEAK NWRN MIN TEMPS AS THEY ARE EXTREMELY CLOSE TO GOING MINS ATTM. ELSEWHERE...DEWPOINTS AND ONLY SLOW DECREASE IN COVG LOOK LIKE THE MINS ARE OKAY FOR NOW. PREV... STUBBORN...ALBEIT SHALLOW STRATO CU CLOUD DECK TRAPPED BELOW A MODERATELY STRONG SUBSIDENCE INVERSION /BASED AT AROUND 2-3KFT AGL/ WILL PERSIST ACROSS MUCH OF NORTHERN AND WESTERN PENNSYLVANIA LATE TODAY INTO SATURDAY...WHILE PARTIAL CLEARING OCCURS ACROSS THE LOWER SUSQ VALLEY AND SURROUNDING AREAS. TEMPS WILL REMAIN STEADY THROUGH LATE THIS AFTERNOON UNDER THE 10-15 KT NWRLY FLOW. READINGS WILL VARY FROM THE MID TO UPPER 20S ACROSS THE NORTHERN AND WESTERN MOUNTAINS...TO THE LOWER 40S IN THE SOUTHEAST. A WEAK SFC RIDGE WILL MOVE TO NEAR THE PENN/OHIO BORDER BY 12Z SATURDAY...BUT THE WEAK WESTERLY ISENTROPIC LIFT ALONG THE 285K THETA SFC...AND SOME SHALLOW MOISTURE BEING ADVECTED SWD INTO THE NRN MTNS OF PENN FROM LAKE ONTARIO...WILL MAINTAIN MOSTLY CLOUDY TO CLOUDY SKIES. LITTLE MORE THAN A FEW FLURRIES OR SPOTTY -FZDZ WILL FALL FROM THIS THIN CLOUD LAYER ACROSS THE HIGHER TERRAIN OF THE LAURELS AND INVOF KBFD. AFTER A PTLY CLOUDY LATE AFTERNOON AND EVENING IN THE SE PART OF THE CWA...A BKN LAYER OF STRATO CU IS EXPECTED TO DRIFT SE /OR FORM/ ACROSS THE REGION OVERNIGHT. DUE TO THE NW-SE GRADIENT OF DECREASING CLOUDS...LOW TEMPS AT DAYBREAK SAT WILL BE IN A RATHER TIGHT RANGE...FROM THE UPPER TEENS TO LOWER 20S ACROSS THE MOUNTAINS...TO THE LOWER 20S IN THE SE && .SHORT TERM /8 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... A RIDGE OF HIGH PRESSURE...LIGHTER WIND...AND ASSOC DRIER AIR MASS WILL BUILD EAST ACROSS THE STATE SATURDAY...PROVIDING THE AREA WITH FAIR WEATHER. HIGH RES MODEL DATA CONTINUES TO PAINT A MOSTLY CLOUDY PICTURE FOR MUCH OF THE REGION SATURDAY INTO SATURDAY NIGHT...THOUGH PERIODS OF SUNSHINE ARE LIKELY THROUGHOUT THE CENTRAL RIDGE AND VALLEY REGION...AND SUSQUEHANNA RIVER VALLEY. WAA ALOFT IN ADVANCE OF SHORTWAVE LIFTING OUT OF THE MISS VALLEY WILL LIKELY SPREAD SOME THIN CIRRUS OVER THE LOWER/THIN STRATO CU CLOUD DECK PRESENT ACROSS THE REGION SATURDAY. ALL 12Z OPERATIONAL MODEL DATA CONTINUES TO SUPPORT A DRY DAY WITH SFC RIDGE AND LOW PWAT AIRMASS OVR THE STATE. MAX TEMPS SHOULD BE FAIRLY CLOSE TO SEASONAL NORMS NEAR 30 ACROSS THE MTNS...AND MID TO UPPER 30S IN THE SE. MOSTLY CLOUDY SKIES WITH LIGHT WIND SAT NIGHT WILL YIELD LOWS IN THE LOWER 20S ACROSS THE MTNS...AND GENERALLY THE MID 20S ELSEWHERE. && .LONG TERM /SUNDAY THROUGH FRIDAY/... HIGH PRES WILL PROVIDE TRANQUIL WEATHER ON SUNDAY...WITH PARTLY TO MOSTLY SUNNY SKIES AND SEASONABLE TEMPS. AFTER THAT...THE WEATHER WILL BECOME INCREASINGLY UNSETTLED AS NEXT WEEK PROGRESSES. CLOUDS WILL INCR SUNDAY NIGHT INTO MONDAY...AS HIGH PRES LOSES ITS GRIP AND A WEAK AREA OF LOW PRES ORGANIZES OVER THE SERN UNITED STATES. LIGHT PRECIP WILL WORK NWD INTO PENNSYLVANIA LATE MONDAY INTO MONDAY NIGHT AND CONTINUE INTO TUES. INITIALLY...CONDS WILL BE COLD ENOUGH FOR THE POSSIBILITY OF SOME WINTRY PRECIP. HOWEVER...WARMER AIR WILL MAKE ITS WAY NWD LATER MONDAY NIGHT INTO TUES AND GRADUALLY CHANGE ANY LINGERING PRECIP OVER TO PLAIN RAIN. A MORE SIGNIFICANT STORM SYSTEM WILL GET ORGANIZED OVER THE MISSISSIPPI VALLEY TUES NIGHT BEFORE PUSHING NWD INTO THE GREAT LAKES ON WED. THIS SYSTEM WILL DRAW EVEN MILDER AIR NWD INTO THE REGION...AND PROVIDE A RAINY AND BREEZY CHRISTMAS EVE DAY. AS THIS SYSTEM DRIFTS NWD INTO SRN CANADA...COLDER AIR WILL WRAP INTO THE REGION ON BLUSTERY WEST WINDS. A CHANGEOVER FROM RAIN TO SNOW SHOWERS FROM WEST TO EAST ACROSS PA IS POSSIBLE LATE WED/WED NIGHT. SCT SNOW SHOWERS WILL CONTINUE INTO THURS ACROSS MAINLY NRN AND WRN PA. THE CHILLIER AIRMASS LOOKS LIKE IT WILL BE SHORT-LIVED...WITH OPERATIONAL MODELS AND THE GEFS SHOWING 850HPA TEMPS ALREADY BEGINNING TO RISE NEXT FRI. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... LLVL NWRLY FLOW AND OROGRAPHIC FORCING OF A SHALLOW MOIST LAYER WILL CONTINUE TO PRODUCE PLENTY OF CLOUDS ACROSS THE NW 1/2 TO 2/3RDS OF THE STATE WITH MAINLY MVFR BKN-OVC CIGS THROUGH TONIGHT. KJST AND KBFD MAY TEETER ON THE UPPER END OF IFR FOR A FEW HOURS LATER TONIGHT /AFTER 06Z/. IN CONTRAST...THE SE PENN AIRFIELDS SUCH AS KMDT...KTHV AND KLNS WILL SEE MAINLY VFR...WITH SKY CONDITIONS VARYING SCT-BKN030-040. NORTHWEST WINDS OF 10-15 KTS WITH HIGHER GUSTS WILL DECREASE TO 8 KTS OR LESS LATER TONIGHT AND SATURDAY. HIGH PRESSURE BUILDS EAST ACROSS PENN SATURDAY...WITH BKN-OVC CIGS VARYING BETWEEN MVFR OVER THE HIGHER TERRAIN OF THE NORTH AND WEST...TO SCT-BKN VFR IN THE VALLEYS. OUTLOOK... SUN...NO SIG WX EXPECTED. MON...LOW CIGS WITH LGT RAIN/SNOW POSSIBLE. BECOMING BREEZY. TUE...LOW CIGS WITH RAIN LIKELY. BREEZY. WED...MILD WITH PERIODS OF RAIN OF VARYING INTENSITY...LEADING TO MVFR TO IFR. ALSO...WINDY WITH LLWS. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LAMBERT NEAR TERM...DANGELO/LAMBERT SHORT TERM...LAMBERT LONG TERM...EVANEGO AVIATION...LAMBERT/CERU

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